Spray cooling for continuous cast strand

ABSTRACT

A plurality of nozzles, lying in spaced apart planes normal to the longitudinal axis of the cast strand, are disposed obliquely to the faces of the cast strand and in zones outside of the regions in which the liquid metal issuing from a breakout flows.

I I Q 7 Q i United States Patent 1 1 [1 1 3,730,258 Easton l [4 1 May 1, 1973 SPRAY COOLING F OR CONTINUOUS [56] References Cited CAST STRAND 75 ,1 UNITED STATES PATENTS l t R l E P ,P a 1 men or U asmn msburgh 3 2,770,021 1/1956 Haner, Jr. et 1. ..l64/8 9 l Assigneez pp p y Inc. Pittsburgh, 3,374,826 3/l968 BlackJr. ..l64/82 v a .1 .Pa, FOREIGN PATENTS OR APPLICATIONS I [221 Filed May 1971 1,476,702. 3/1967 France ..l64/283 N 970,284 9/l964 Great Britain 7 Related US. Application Data Primary g gp g Asfiear Attome erman at er et [63] Continuation-impart of Ser. No. 868,093, Get. 21, y i I 1969, abandoned. [57] ABSTRACT A plurality of nozzles, lying in spaced apart planes 0 (gl ..l64/2B8232,dl normal to the longim i a1 axisof the cast Strand, are 5 Fieid l f 82 89 283 disposed obliquely to the faces of the cast strand and in zones outside of the regions inwhich the liquid metal issuing from a breakout flows.

6 Claims, sol-swi Figures Patten ted May '1, 1973 2 Sheets-Sheet 1 INVENTOR. RUFUS 4570 BY 5% Patented May 1, 1973 2 Sheets-Sheet 2 INVENTOR RUFUS 54.9mm JMM SPRAY COOLING FOR CONTINUOUS CAST STRAND CROSS REFERENCE TO RELATED APPLICATION This is a continuation-in-part of application Ser. No. 868,093 filed Oct. 21 1969, now abandoned.

BACKGROUND OF THE INVENTION tinuous cast strand.

In continuous casting machines, it is necessary and customary to cool the relatively thin skin of solid metal which forms a continuous cast strand to prevent the molten metal core of the strand from reheating the skin and causing a breakout of molten metal. Such breakouts, when they occur, result in a shutting down of the continuous casting machine and a serious loss of production. I I

The usual way in which the strand is cooled is to arrange a plurality of spray nozzles in spaced apart vertical planes that are normal to the longitudinal axis of the cast strand, with the spray nozzles in each plane directed normal to a surface of the cast strand. It is also customary to provide a single nozzle at each corner of the cast strand, such nozzles being located in a horizontal plane situated just below the bottom of the mold.

When a breakout occurs, however, the nozzles directly opposite the breakout are covered by the outpouring molten metal, and it is usually necessary to remove and to replace the nozzles damaged by the molten metal.

It is known that, in a rectangular or square cast strand, the skin of the cast strand is thinner at two diagonally opposite corners. Thus, breakouts are more likely to occur at such corners than in the middle of the cast strand.

Those skilled in the art will recognize from the following description of one embodiment of the invention, how the present invention overcomes the problem of damaged spray nozzles when breakouts occur.

SUMMARY OF THE INVENTION A plurality of spray nozzles are disposed in spaced apart planes that are normal to the cast strand and the nozzles in each plane are oriented toward the surfaces of the strand, but they lie outside of major and minor zonal areas wherein breakouts are more and less likely to occur. I

For a further understanding of the invention and for features and advantages thereof, reference may be made tothe following description taken in conjunction with the drawing which shows, for the purpose of exemplification, one embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. I is a schematic cross-sectional view of a cast strand cooled by spray nozzles in accordance with the teaching of the prior art;

- FIG. 2 is a schematic cross-sectional view of a cast strand cooled by spray nozzles in accordance with the present invention; and

FIG. 3 is a schematic view similarto that of FIG. 2, but showing additional features thereof.

DETAILED DESCRIPTION Referring to FIG. 1, a newly formed cast strand 1!, which is just emerging from a continuous casting mold has a relatively thin skin 13 that surrounds a core 15 of molten metal. A plurality of spray nozzles 17 are disposed in a plane that is perpendicular to the longitu dinal axis of the cast strand 11. Each spray nozzle 17 lies in a plane 18 disposed normal to a respective surface of the strand 11 at its mid point. I

From FIG. 1 it will be noticed that the nozzles 17 are relatively close to the surface of the cast strand 11 and it will be recognized that corner nozzles (not shown) are usually installed along corner angle bisectors extended and very close to the strand corner.

Now, should a breakout occurin a side of the strand 1 1, the molten metal of the core 15 will exude from the ruptured skin 13 and will contact and freeze onto a number of spray nozzles 17 disposed vertically below the breakout. Thus, the spray nozzles 17 are ruined by' the molten metal, and they must be removed and replaced during the laborious cleaning up operations.

FIGS. 2 and 3 illustrate an arrangement of spray nozzles in accordance with the invention that are disposed in spaced apart planes normal to the center line longitudinal axis of a similar cast strand 21. But, the nozzles 19 are arranged in vertical planes 23 disposed at an acute angle, A, with respect to planes 25'normal to the midpoint of a surface of the cast strand 21. The spray nozzles 19, then, are so disposed that, when a breakout occurs in any surface of the cast strand 2l,the exuding molten core metal 27 will not contact and thereby damage the spray nozzles 19.

Referring to FIG. 3, those skilled in the art will recognize four major zones 29 and two minor zones 31.

Experience teaches that breakouts in the thin shell of the cast strand occur most likely in the major zones and that breakouts occur less likely in the minor zones. Then, for each zone, the ordinate of the curve shown in FIG. 3, defining the zonal area, represents the relative probability of a breakout occurring at that particular location on the surface of the caststrand 21. The area defined by such curve also represents an area of hazard due to molten metal 27 spewing from a breakout in the thin skin of the cast strand 21. i

For example, in FIG. 3, the skin of the cast strand is known to be much thinner at two diagonally opposite corners 33, 35 than at the other corners 37, 39. Therefore, it is more probable that a breakout would occur in the shell in the major zones close to the corners 33, 35. The ordinates of the major zonal area 29, then, are greatest at the corners 33, 35. I

Likewise, there .is almost no probability that a breakout will occur at the other corners37, 39. In fact,

the probability vanishes some short distance from the 7 from a breakout would then impinge on and freeze to such nozzles 17. These nozzles would have to be removed and replaced during clean-up operations. But, the nozzles 19 of the present invention are disposed at an angle A from the normal plane 25, which places such nozzles well outside of the zonal areas 29, 31 of both the major and the minor hazards.

Those skilled in the art will understand that the angle A may be determined by a functional relation of the distance the nozzle 19 is from the cast strand and the shape of the probability zonal areas. In any case, the nozzles 19 lie outside of such zonal areas. A suggested angle A is about 30.

Further, prior art nozzles usually emit so-called flat spray patterns. That is, the water of the spray flows in a horizontal plane. But, the nozzles 19 of the present invention are so designed that they emit a conical spray pattern. Hence, more effective cooling is achieved and fewer nozzles are required.

Although the invention has been described herein with a certain degree of particularity, it is understood that the present disclosure has been made only as an example and the scope of' the invention is defined by what is hereinafter claimed.

What is claimed is:

1. In a continuous casting apparatus wherein a cast strand continuously emerges from a mold into which molten metal is poured, the improvement comprising:

a. a plurality of spray nozzles arranged in spaced apart horizontal parallel planes disposed normal to the axis of said cast strand, with the nozzles in each plane being oriented toward the surface of said strand,

i. each said horizontal plane containing major and minor areas abutting the surface of said strand where the shell of said casting is normally the thinnest and where breakouts are more likely to occur, and with ii. each said nozzle lying in an area of said plane that is not in a major zone or in a minor zone and being oriented toward at least one surface of said casting.

2. The improvement of claim 1 wherein:

a. said major zones abut the flat sides of a cast strand having a polygonal cross section.

3. The improvement of claim 1 wherein:

a. said minor zone is associated with the angular bisectors extended of the angles at the comers of a cast strand having a polygonal cross section.

4. In a continuous casting apparatus wherein a cast strand continuously emerges from a mold into which molten metal is poured, the improvement comprising:

a. a plurality of spray nozzles arranged in spaced apart parallel planes disposed normal to the axis of said cast strand, with i. each nozzle being oriented at an acute angle toward at least one surface of said cast strand, with ii. each parallel plane containing major areas abutting the surface of said cast strand where the shell is normally the thinnest and where breakouts are most likely to occur, and minor areas abutting the surface of said cast strand wherein said breakouts are less likely to occur,

iii. s i'd major zonal areas extending outwardly from the sides of a cast strand having a polygonal cross section, and with iv. said minor zonal areas extending outwardly from and on opposite sides of the corner angle bisectors extended of said polygonal cross section, and with v. each said nonle lying in an area of said plane that is not in a major zone or in a minor zone.

. The improvement of claim 4 wherein:

a. said acute angle is about 30 measured counterclockwise from a plane that is normal to said cast strand at the midpoint of each surface thereof.

The improvement of claim 4 wherein:

. the spray nozzles in each horizontal plane emit conical spray patterns and each side of said cast strand is included in the spray pattern of a respective spray nozzle; and wherein b. the axis of each nozzle intersects the side of said cast strand at a point that is not the midpoint of said side. 4 

1. In a continuous casting apparatus wherein a cast strand continuously emerges from a mold into which molten metal is poured, the improvement comprising: a. a plurality of spray nozzles arranged in spaced apart horizontal parallel planes disposed normal to the axis of said cast strand, with the nozzles in each plane being oriented toward the surface of said strand, i. each said horizontal plane containing major and minor areas abutting the surface of said strand where the shell of said casting is normally the thinnest and where breakouts are more likely to occur, and with ii. each said nozzle lying in an area of said plane that is not in a major zone or in a minor zone and being oriented toward at least one surface of said casting.
 2. The improvement of claim 1 wherein: a. said major zones abut the flat sides of a cast strand having a polygonal cross section.
 3. The improvement of claim 1 wherein: a. said minor zone is associated with the angular bisectors extended of the angles at the corners of a cast strand having a polygonal cross section.
 4. In a continuous casting apparatus wherein a cast strand continuously emerges from a mold into which molten metal is poured, the improvement comprising: a. a plurality of spray nozzles arranged in spaced apart parallel planes disposed normal to the axis of said cast strand, with i. each nozzle being oriented at an acute angle toward at least one surface of said cast strand, with ii. each parallel plane containing major areas abutting the surface of said cast strand where the shell is normally the thinnest and where breakouts are most likely to occur, and minor areas abutting the surface of said cast strand wherein said breakouts are less likely to occur, with iii. said major zonal areas extending outwardly from the sides of a cast strand having a polygonal cross section, and with iv. said minor zonal areas extending outwardly from and on opposite sides of the corner angle bisectors extended of said polygonal cross section, and with v. each said nozzle lying in an area of said plane that is not in a major zone or in a minor zone.
 5. The improvement of claim 4 wherein: a. said acute angle is about 30* measured counterclockwise from a plane that is normal to said cast strand at the midpoint of each surface thereof.
 6. The improvement of claim 4 wherein: a. the spray nozzles in each horizontal plane emit conical spray patterns and each side of said cast strand is included in the spray pattern of a respective spray nozzle; and wherein b. the axis of each nozzle intersects the side of said cast strand at a point that is not the midpoint of said side. 